In recent years, in correspondence with the spread of personal computers, a digital cameral for easily reading images into a personal computer is in wide use. Further, incorporation of a digital camera into an information processor such as a mobile computer, a portable telephone, or a personal digital assistant (PDA) is generalized. In correspondence with the spread of such a digital camera, a smaller digital camera is requested, thus further miniaturization of an imaging optical unit is required.
Therefore, to make the imaging optical unit compact, proposals of bending the imaging optical system halfway the optical path, thereby realizing miniaturization thereof without changing the optical path length even if the magnification is changed are made (Patent Documents 1 and 2). According to the proposals, a reflection member is arranged on the optical path, and the optical path is bent about 90 degrees, and then an optical image is formed on an image pickup device by a rear lens group.
However, in the two patent documents aforementioned, the lenses are arranged on the side of an subject from the reflection member, so that the size of the digital camera in the depth direction is restricted by the distance between the reflection member and the lenses on the subject side.
To solve this problem, proposals of moving the reflection member and retracting the lenses into the space formed by movement of the reflection member, thereby making the apparatus compact when not in use are made (Patent Documents 3 and 4).
Patent Document 1: Japanese Laid-Open Patent Publication No. 2000-131610
Patent Document 2: Japanese Laid-Open Patent Publication No. 2004-69808
Patent Document 3: Japanese Laid-Open Patent Publication No. 2003-43354
Patent Document 4: Japanese Laid-Open Patent Publication No. 2003-169236
In reality, in Patent Documents 3 and 4, when switching the reflection member from the usage state to the retracted state, the reflection member is moved to a position within the movable range of the rear lens group along the guide shaft and when switching it from the retracted state to the usage state, the reflection member is moved to a predetermined position on the optical axis, and the lenses are moved to predetermined positions on the optical axis by another moving means.
However, in this constitution, to ensure the movement distance of the imaging optical system due to zooming of the rear lens group, it is necessary to increase the overall length or to ensure the storage space of the reflection member, a complicated structure for collapsing the rear lens group is necessary. Further, in the usage state for imaging, the lenses and reflection member are moved by an individual moving means and the lenses and reflection member are held by an individual holding member, so that eccentricity occurs in the optical axis between the lenses and the reflection member, thus the image quality of the imaging optical system deteriorates. Furthermore, the lenses and reflection member are held by an individual holding member and an individual moving means is necessary, so that the number of parts is increased, and the structure is complicated, and the manufacturing cost is increased.